1. Field of the Invention
The present invention relates to a wideband code division multiple access (WCDMA) terminal system, and particularly, to an apparatus and a method for processing a paging in the WCDMA terminal.
2. Description of the Background Art
In a WCDMA mobile communication system, a base station uses a paging indicator channel (PICH) in order to provide a WCDMA terminal with information about the system or to notify the WCDMA terminal of a call.
The PICH is a fixed rate physical channel, and a paging indicator (PI) is transmitted from the base station through the PICH. Generally, a plurality of different WCDMA terminals are grouped together to form a ‘receiving group’. Each WCDMA terminal belongs to a particular receiving group. The PI identifies a particular receiving group to which a particular WCDMA terminal (for which a paging is intended), belongs. That is, the PI carries information specifying the intended receiving group associated with the current paging.
FIG. 1 shows a configuration of the PICH and a secondary common control physical channel (SCCPCH) used in a general WCDMA system.
Referring to FIG. 1, The PICH is repeatedly transmitted at every frame during a certain section. Here, one frame is 10 ms. The PICH is always related to the SCCPCH including a paging channel (PCH). There is a time difference of as much as TPICH between the PICH frame and the SCCPCH frame related to the PICH frame. That is, when a PI is set in the PICH, the PCH including a paging message is transmitted through the SCCPCH. The SCCPCH is transmitted after the TPICH time has elapsed since the PICH had been transmitted. Herein, the TPICH time means 7680 chips and corresponds to 3 slots (2 ms).
FIG. 2 shows a configuration of a general WCDMA terminal for processing a paging.
As shown therein, the WCDMA terminal generally comprises: a radio frequency (RF) unit 1 for down-converting a frequency of an RF signal received through an antenna; an analog base band unit (ABB) 2 for demodulating a signal outputted from the RF unit 1 and thereby outputting a data frame; and a digital base band unit (DBB) 3 for modulating the data frame from the ABB 2 to identify whether or not there is a paging and for accessing the paging message if there is a paging.
Operations for processing a paging of the general WCDMA terminal will be described as follows.
When a paging for a certain WCDMA terminal is generated, the WCDMA system sets a PI of a PICH to identify a receiving group having a particular WCDMA terminal for which the paging is intended. That is, the PI as set indicates the presence of a paging for the identified receiving group. After that, the WCDMA system transmits repeatedly the PICH including the set PI at every frame in predetermined sections.
The WCDMA terminal is operated according to a discontinuous received (DXR) cycle in order to interpret the PICH. The DXR cycle is a period for demodulating the PCH. That is, during a preparing time dRF shown in FIG. 1, the RF unit 1 and the ABB 2 of the WCDMA terminal demodulate an RF signal to output the data frame(s). Then the DBB 3 analyzes the PI of the PICH in the data frame. If the PI identifies the receiving group to which the present WCDMA terminal belongs (i.e., the current paging is for the current WCDMA terminal's receiving group), then the DBB 3 examines the PCH of the SCCPCH after a predetermined time (TPICH time) elapses, and analyzes the PCH of the SCCPCH. Thereafter, the DBB 3 checks if the current paging is specifically for the current WCDMA terminal and if so, extracts a page message from the analyzed PCH.
TABLE 1Time orderRF unitABBDBBt1~t2ONON(OFF)t2~t3ONONONt3~t4OFFOFF(OFF)t4~t5ONONON
Table 1 is a table for analyzing electric power supplied to the RF unit 1, the ABB 2 and the DBB 3 when the general WCDMA terminal operates the paging process.
As described above, the general WCDMA terminal obtains the PICH frame by operating the RF unit 1 and the ABB 2 during the preparing time dRF (t1˜t2), and interprets the PICH frame during the time t2˜t3 by operating the DBB 3 when it receives the PICH frame. If the PI of the interpreted PICH corresponds to the receiving group to which the current WCDMA terminal belongs, then the DBB 3 of the WCDMA terminal examines and interprets the PCH of the SCCPCH during 10 ms after a predetermined time (TPICH) has elapsed.
However, the general WCDMA terminal checks whether or not the WCDMA terminal is paged using only the software of the DBB 3. Thus, the DBB 3 must be operated (turned on) at all times in order to check the paging according to the DXR cycle, even in case that the WCDMA terminal is not paged. This procedure places heavy processing loads on the DBB 3. Further, it become more difficult and time consuming to modify certain reference values used to compare with the PI in the general WCDMA terminal because all the paging processes are performed by running the software of the DBB 3 and the software must be modified.
Also, in the general WCDMA terminal, since all the paging processes are performed using the DBB 3, the electric power is supplied to the RF unit 1, the ABB 2 and the DBB 3 during a minimum (10 ms+dRF) period (in case that the PI does not designate the particular receiving group to which the current WCDMA terminal belongs)˜a maximum (22 ms+dRF) period (in case that the PI designates the current terminal's receiving group). As a result, the power consumption by the general WCDMA terminal is high.